The documentation stated that writing to HV_X64_MSR_CRASH_CTL unconditionally causes the guest to shutdown. In reality, it triggers qemu_system_guest_panicked() via KVM_SYSTEM_EVENT_CRASH and the resulting action depends on the generic panic action policy (-action panic=...), which defaults to shutdown.
Reviewed-by: Vitaly Kuznetsov <[email protected]> Signed-off-by: Marc-André Lureau <[email protected]> Message-ID: <[email protected]> --- docs/system/i386/hyperv.rst | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/docs/system/i386/hyperv.rst b/docs/system/i386/hyperv.rst index 1c1de77feb65..e1babffb0f99 100644 --- a/docs/system/i386/hyperv.rst +++ b/docs/system/i386/hyperv.rst @@ -71,8 +71,11 @@ Existing enlightenments by the guest when it crashes, HV_X64_MSR_CRASH_P0..HV_X64_MSR_CRASH_P5 MSRs contain additional crash information. This information is outputted in QEMU log and through QAPI. - Note: unlike under genuine Hyper-V, write to HV_X64_MSR_CRASH_CTL causes guest - to shutdown. This effectively blocks crash dump generation by Windows. + Note: unlike under genuine Hyper-V, write to HV_X64_MSR_CRASH_CTL triggers + ``qemu_system_guest_panicked()`` via ``KVM_SYSTEM_EVENT_CRASH`` and the + resulting action depends on the ``-action panic=...`` policy (default: + ``shutdown``). With the default action, this effectively blocks crash dump + generation by Windows. ``hv-time`` Enables two Hyper-V-specific clocksources available to the guest: MSR-based @@ -304,8 +307,9 @@ currently implemented Hyper-V enlightenments with the following exceptions: ``hv-version-id-snumber`` can be left unchanged, guests are not supposed to behave differently when different Hyper-V version is presented to them. - ``hv-crash`` must only be enabled if the crash information is consumed via - QAPI by higher levels of the virtualization stack. Enabling this feature - effectively prevents Windows from creating dumps upon crashes. + QAPI by higher levels of the virtualization stack. With the default + ``-action panic=shutdown`` policy, enabling this feature effectively + prevents Windows from creating dumps upon crashes. - ``hv-reenlightenment`` can only be used on hardware which supports TSC scaling or when guest migration is not needed. - ``hv-spinlocks`` should be set to e.g. 0xfff when host CPUs are overcommited -- 2.55.0
